Chain slipping off front cog?

[cardiffgareth]

Hello!
Post 3 and another tech question!

If I pedal normally, i.e. not hard all is good with the chain and cogs but if I put it into a high gear and really push hard on the pedals as if to build up speed every now and then it clunks and its like the chain slips off the front cog, like its missing a tooth on the front cog? Only briefly and then all is good again for a while and it'll do it again?

I thought maybe the chain was worn as to me (and I'm no expert!) but the front cogs look good to me so I went to Halfords to buy a new chain but he said it could be the front bearing thing that screws into the frame and to check the pedals for side play. Done that and they're rock solid with no movement. He also said it could be the front derailleur hitting the chain and causing it but looking at it the front derailleur isn't touching the chain?

Any ideas ?

Thanks in advance!

 

[midliferider]

Just to understand, your chain really does not fall off but you feel it gives way. Is that correct?

 

[cardiffgareth]

That's right, the chain doesn't come off the front cog, just feel like its missed a cog, make a clunk sound and then its business as usual until it does it again?

 

[raleighnut]

Chain suck? (google it for info)

 

[cardiffgareth]

Chain suck? (google it for info)

Never knew that! Just Googled it and that's me! So, new chain first then and if I still have it then new front cogs as well! At this rate I'll have a complete new bike soon

 

[midliferider]

Hmm, I am doubtful whether what you describe is actually chain suck.
I think it is perhaps due to poor gear tuning. You have a choice.
Measure or check the chain for wear and tear.
If normal, then adjust the gears.

 

[cardiffgareth]

Thanks for the reply

How do I measure and check the chain or is there a 'how to' I've not seen somewhere: lol!
I was just going to buy this chain from Halfords as for the sake of a fiver, thought it would be easier and give me more life in the long run?!
http://www.halfords.com/cycling/bik...peed-116-link-bike-chain-with-connecting-link

 

[midliferider]

There are various ways to decide whether your chain is worn.
The easiest is to use a specific tool that you can buy for under £10.

The trouble in replacing the chain is this. If you replace the chain for the wrong reason, your original problem won't go away.

 

[jonny jeez]

The trouble in replacing the chain is this. If you replace the chain for the wrong reason, your original problem won't go away.

This ^^^ plus there is a method that suggests replacing the chain should be accompanied by replacement of the block (cassette or rear cogs) at the same time.

which puts the cost from a tenner up to around £50

so whilst a cheap chain replacement seems an attractive fix, it may not address the issue.

 

[jonny jeez]

Hello!
Post 3 and another tech question!

If I pedal normally, i.e. not hard all is good with the chain and cogs but if I put it into a high gear and really push hard on the pedals as if to build up speed every now and then it clunks and its like the chain slips off the front cog, like its missing a tooth on the front cog? Only briefly and then all is good again for a while and it'll do it again?

I thought maybe the chain was worn as to me (and I'm no expert!) but the front cogs look good to me so I went to Halfords to buy a new chain but he said it could be the front bearing thing that screws into the frame and to check the pedals for side play. Done that and they're rock solid with no movement. He also said it could be the front derailleur hitting the chain and causing it but looking at it the front derailleur isn't touching the chain?

Any ideas ?

Thanks in advance!

I suspect its actually your block that is slipping...the rear group of cogs. I suspect you only need to trim the indexing a fraction and the problem will cure.

That would be my first port of call as its a five minute job and costs nothing.

If that isn't the case then look into a new chain and block, then maybe new rings but that all sounds like massive overkill to me at this stage.

This video will walk you through it and make you an instant expert!

.

 

[raleighnut]

This ^^^ plus there is a method that suggests replacing the chain should be accompanied by replacement of the block (cassette or rear cogs) at the same time.

which puts the cost from a tenner up to around £50

so whilst a cheap chain replacement seems an attractive fix, it may not address the issue.

£50 is a bit high, it should be easy to replace them for half that.

 

[midliferider]

£50 is a bit high, it should be easy to replace them for half that.

But whatever the cost, the original problem won't go away as it has not been addressed.

 

[jonny jeez]

£50 is a bit high, it should be easy to replace them for half that.

I guess so but I was working on £35 for the block and a tenner for the chain.

Either way though, I suspect its an indexing issue

 

[jonny jeez]

Hello!
Post 3 and another tech question!

If I pedal normally, i.e. not hard all is good with the chain and cogs but if I put it into a high gear and really push hard on the pedals as if to build up speed every now and then it clunks and its like the chain slips off the front cog, like its missing a tooth on the front cog? Only briefly and then all is good again for a while and it'll do it again?

I thought maybe the chain was worn as to me (and I'm no expert!) but the front cogs look good to me so I went to Halfords to buy a new chain but he said it could be the front bearing thing that screws into the frame and to check the pedals for side play. Done that and they're rock solid with no movement. He also said it could be the front derailleur hitting the chain and causing it but looking at it the front derailleur isn't touching the chain?

Any ideas ?

Thanks in advance!

So, Gareth...is it all sorted?